Victor has fainted. The word "lifeless" had a broader range of
signification in Mary Shelley's day than it does now.
Johnson's 1755 Dictionary offers
three meanings for the adjective, only the first, which is the modern
definition, being inappropriate to Victor's state.
1. Dead; deprived of life.
2. Unanimated; void of life.
3. Without power, force, or spirit.